Low power self-oscillating converters with FET type power switches tend to become operationally unstable when operating into a load that is very small with respect to its rated load (i.e. typically 10% or less of rated load). This unstable behavior is normally manifested as a low frequency oscillation called bursting in which the FET power switch operates for several switching cycles and then remains off for several cycles. The effect of the unstable behavior is to cause the ripple on the output voltage to increase significantly, frequently exceeding the specified output voltage ripple of the converter by an order of magnitude. This places restrictions on the load range over which such a selfoscillating converter may be operated and limits its range of applications.
This problem of bursting at light loads has been dealt with in the prior art by connecting a bleeder resistor across the output of the self-oscillating converter to artificially increase the load. Addition of the bleeder resistor however dissipates a considerable amount of power, reducing the efficiency of the self-oscillating converter and reduces its maximum power output capability.